DL backhaul control channel design for relays

ABSTRACT

Methods and apparatus are described for providing compatible mapping for backhaul control channels, frequency first mapping of control channel elements (CCEs) to avoid relay-physical control format indicator channel (R-PCFICH) and a tree based relay resource allocation to minimize the resource allocation map bits. Methods and apparatus (e.g., relay node (RN)/evolved Node-B (eNB)) for mapping of the Un downlink (DL) control signals, Un DL positive acknowledgement (ACK)/negative acknowledgement (NACK), and/or relay-physical downlink control channel (R-PDCCH) (or similar) in the eNB to RN (Un interface) DL direction are described. This includes time/frequency mapping of above-mentioned control signals into resource blocks (RBs) of multimedia broadcast multicast services (MBMS) single frequency network (MBSFN)-reserved sub-frames in the RN cell and encoding procedures for these. Also described are methods and apparatus for optimizing signaling overheads by avoiding R-PCFICH and minimizing bits needs for resource allocation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/621,724, filed Feb. 13, 2015, which is a continuation of U.S. patentapplication Ser. No. 12/855,331, filed Aug. 12, 2010, which issued asU.S. Pat. No. 8,976,806 on Mar. 10, 2015, and claims the benefit of U.S.Provisional Patent Application No. 61/256,159, filed Oct. 29, 2009, andU.S. Provisional Patent Application No. 61/234,124, filed Aug. 14, 2009,the contents of both of which are incorporated by reference herein intheir entirety.

BACKGROUND

Relaying is used as a technology to enhance coverage and capacity,(e.g., long term evolution advances (LTE-A) system information (SI)),and offers more flexible deployment options. Relaying may be used withother technologies as well. For example, a type I relay may be includedas one of the technology components for LTE-A. A type I relay createsnew cells, distinguishable and separate from the cells of a donor eNodeB(eNB). To any legacy release 8 (R8) wireless transmit/receive unit(WTRU), a type I relay may appear as an eNB, (i.e., the presence of atype I relay in its communication path to the donor eNB is transparentto the WTRU). A type I relay node (RN) may be described as an eNB thathas a wireless in-band backhaul link back to the donor eNB by using anLTE or LTE-A air interface within the international,mobile-telecommunications (IMT) spectrum allocation.

SUMMARY

Methods and apparatus are described for providing compatible mapping forbackhaul control channels, frequency first mapping of control channelelements (CCEs) and tree based relay resource allocation. Methods andapparatus for mapping of control signals, such as Un downlink (DL)control signals, between a base station (e.g., eNB) and a relay node(e.g., type I relay node) are described. This includes time-frequencymapping of the control signals into RBs of MBSFN-reserved sub-frames inthe RN cell and encoding procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 shows duplexing diagram for a relay for which the methods hereincan be implemented;

FIG. 3 shows an example of backhaul control channel mapping;

FIG. 4 illustrates a non-limiting, exemplary mapping of an R-PHICH andR-PDCCH over an OFDM symbol when R-PCFICH is not used;

FIG. 5 illustrates a non-limiting, exemplary mapping of an R-PHICH andR-PDCCH over an OFDM symbol when R-PCFICH is used;

FIG. 6A illustrates a non-limiting, exemplary method of implementingmapping of an R-PDCCH by a eNB;

FIG. 6B illustrates a non-limiting, exemplary mapping of R-PDCCH intoOFDM symbols;

FIG. 6C illustrates a non-limiting, exemplary method of implementingdecoding of R-PDCCH by a relay;

FIG. 7A illustrates a non-limiting, exemplary method of implementingmapping of an R-PDCCH by a eNB;

FIG. 7B illustrates a non-limiting, exemplary mapping of R-PDCCH intoOFDM symbols;

FIG. 7C illustrates a non-limiting, exemplary method of implementingdecoding of R-PDCCH by a relay;

FIG. 8 shows a reduced bit map for resource allocation.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications-system 100 may bea multiple access system and may employ one or more channel, accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another-RAN (notshown) employing a GSM radio technology.

The core-network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 18 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source. 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1 may include a mobility managementgateway (MME) 142, a serving gateway 144, and a packet data network(PDN) gateway 146. While each of the foregoing elements are depicted aspart of the core network 106, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 142 may be connected to each of the eNode-Bs 142 a, 142 b, 142 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

It is one fundamental design principle of frequency division duplex(FDD)-based in-band relaying that a type I RN cannot simultaneouslytransmit to a WTRU on the access link while receiving from the donor eNBon the backhaul link in the downlink (DL) shared access and backhaulfrequency channel, or receive from a WTRU on the access link whiletransmitting to the donor eNB on the uplink (UL) shared access andbackhaul frequency channel.

During radio access network (RAN) 1#56, it has been agreed thatmultimedia broadcast multicast services (MBMS) single frequency network(MBSFN) sub-frames may be used as a means to allow backward compatibleimplementation of relaying and to allow for donor eNB to RNtransmissions on the DL frequency channel respecting the legacy R8 framestructure.

MBSFN sub-frame allocation is limited to six (6) sub-frames per frame,(for LTE FDD mode), and no MBSFN sub-frame may be configured insub-frames #0, #4, #5 and #9 in the case of frame-structure type 1.

During RANI#57, the principles of DL access link and DL backhaul linksub-frame boundary alignment and semi-static assignment of time-domainresources for the DL backhaul link have been accepted. In addition, theintroduction of relay physical downlink shared channel (R-PDSCH),relay-physical uplink shared channel (R-PUSCH) and relay-physicaldownlink control channel (R-PDCCH) has been agreed.

A RN deployment is shown in FIG. 2. For Type 1 (inband) relays, the RN230 to eNB 225 link 210 must operate on the UL carrier, and the eNB 225to RN 230 link 245 must operate using the DL carrier. The eNB 225 to RN230 link 245 and the RN 230 to UE2 235 link 240 share the same DLcarrier frequency, and similarly the RN 230 to eNB 225 link 210 and theUE2 235 to RN 230 link 205 share the same UL carrier.

From the macro eNB 225 perspective, the RN 230 may appear as a regularor as a special WTRU, while simultaneously, the RN 230 may appear as aregular eNB to UE2 that is being served by the RN 230, (i.e., the UE2camps on and gets service from the RN 230 in a way that is the same asfrom a regular eNB). For illustration purposes in FIG. 2, it is assumedthat UE1 is a WTRU that is served by the macro eNB 225, and UE2 is aWTRU that is served by the RN 230.

Since the RN 230 cannot simultaneously transmit (Tx) and receive (Rx) inthe same DL frequency band (F1), the eNB 225 to RN 230 and RN 230 to UE2235 links (i.e., links 245 and 250) are time multiplexed as they sharethe same carrier. Similarly, the RN 230 to eNB 225 and UE2 235 to RN 230links (i.e., links 210 and 215) are also time multiplexed in the ULfrequency band F2.

In other words, the RN 230 operates as a FDD-eNB from UE2 235perspective, but the RN 230 itself has to support TDD operation (Tx andRx switching) in both DL and UL carriers. Note that there is no impacton the eNB 225 as it operates in the usual fashion (DL Tx on F1, and ULRx on F2).

The time-multiplexing of the eNB 225 to RN 230 and RN 230 to UE2 235links (i.e., links 245 and 250) can be efficiently supported via theflexible MBSFN signaling provided by LTE R8 specifications. The RNconfigures some (up to a maximum of 6) sub-frames in the RN cell asMBSFN-reserved sub-frames. Therefore, relay WTRUs will only expect andattempt to decode the control region in these, but not expect any DLassignments or PDSCH transmission. Note that the MBSFN-reservedsub-frames in the Relay cell might not necessarily appear to the WTRUserved by the donor eNB cell as MBSFN sub-frames. Moreover, thesereserved sub-frames in the Relay cell might not appear to the Relay onthe backhaul link as an MBSFN sub-frames in the sense of providing MBMSservices. In a MBSFN reserved sub-frame, the RN first transmits in theDL access link in the control region, followed by some Tx to Rxswitching time (for example, 1 symbol), and receiving itselftransmissions from the eNB on the DL backhaul link.

In the DL, the donor eNB can in principle transmit DL assignments (andPDSCH), DL positive acknowledgements (ACKs)/negative acknowledgements(NACKs) on physical hybrid automatic repeat request (HARQ) indicatorchannel (PHICH) and UL grants (for PUSCH) to its served macro WTRUs inany DL sub-frame however in order to avoid self-interference between theRelay transmitter and receiver, the donor eNB should make DLtransmission in sub-frames broadcasted by the RN in its cell as MBSFNsub-frames. Similarly, the RN may transmit DL ACKs/NACKs and UL grantsto its served relay WTRUs in any DL sub-frame. However, in order toavoid self-interference between the Relay transmitter and receiver, theRN may transmit PDSCH to its relay WTRUs only in sub-frames notconfigured as MBSFN sub-frames.

The following operating principles for RN and donor eNB operation havebeen agreed. At the RN, the access link DL sub-frame boundary is alignedwith the backhaul link DL sub-frame boundary (except for possibleadjustment to allow for RN Tx/Rx switching). The set of DL backhaulsub-frames, during which DL backhaul transmission may occur, istime-domain resources (set of sub-frames) that may be used for the DLbackhaul link, and are semi-statically assigned. It has not beendetermined whether the time-domain resources for the UL backhaul linkare to be also semistatically assigned. The set of UL backhaulsubframes, during which UL backhaul transmission may occur, can besemi-statically assigned, or implicitly derived from the DLbackhaul-subframes using the HARQ timing relationship.

A new physical control channel which may be called the relay physicaldownlink control channel (R-PDCCH), may be used to dynamically or“semi-persistently” assign resources, within the semi-staticallyassigned sub-frames, for the DL backhaul data, the relay physicaldownlink shared channel (R-PDSCH). The R-PDCCH is also used todynamically or “semi-persistently” assign resources for the UL backhauldata, the relay physical uplink shared channel (R-PUSCH).

The R-PDCCH may be transmitted on a subset of the physical resourceblocks (PRBs) of the subframes assigned for the DL backhaul link. Apredefined number of resource blocks (RBs) may be reserved for abackhaul control channel. The reserved RBs may be fixed by thespecifications, semi-statically signaled to relay node, or signaled viaany other-channel, e.g., relay-physical control format indicator channel(R-PCFICH). When R-PCFICH or a similar charnel is used to signal thereserved RBs, in order to minimize the overhead, the selection can bemade from a set of predefined patterns. The R-PCFICH itself may belocated in a standard specified RB, (e.g., center of bandwidth). TheR-PDCCH may be transmitted on a subset of the orthogonal frequencydivision multiplexing (OFDM) symbols of the subframes assigned for theDL backhaul link. This subset of OFDM symbols may include the full getof OFDM symbols available for the backhaul link. The R-PDCCH may betransmitted starting from an OFDM symbol within the subframe that islate enough so that the RN can receive it. The R-PDCCH may be used toassign DL resources in the same subframe and/or in one or more latersubframes. The R-PDCCH may be used to assign UL resources in one or morelater subframes. The R-PDSCH and the R-PDCCH may be transmitted withinthe same PRBs or within separated PRBs. The backhaul control channel RBsmay carry R-PDCCH, relay-physical hybrid automatic repeat request (HARQ)indicator channel (R-PHICH) and if needed, R-PCFICH.

Frequency division multiplexing (FDM), time division multiplexing (TDM)and a hybrid multiplexing scheme (TDM+FDM, or equivalently FDM+TDM) arepossible candidates for resource multiplexing between relay resources,(R-PDCCH and R-PDSCH), or between relay resources, (R-PDCCH, R-PDSCH),and non-relays resources, (PDCCH, PDSCH).

Backhaul control channels design may require details of control channelmapping in frequency and time domains at the eNodeB, and decoding at therelay (or any other receiver of R-PDCCH such as a WTRU), of the controlchannels without the use of R-PCFICH. The methods, systems andapparatuses herein support ACK/NACK, reduction of R-PDSCH decodingdelay, reduction of blind, search processing time and related powerconsumption, minimization of the amount of overhead signaling forcontrol channels; and minimization of the bandwidth requirement forcontrol channels.

Relay operation is described herein for the case of in-band, (i.e.,RN-eNB link share the same carrier with RN to WTRU access link), in FDDnetworks. However, methods and procedures described are equallyapplicable to TDD networks. Furthermore, relay design on the Uninterface between a RN and an eNB is described. Specifically, severalmethods and procedures are described of how one or more controlsignal(s), i.e., eNB to RN DL ACK/NACK and R-PDCCH to carry Un DLassignments or Un UL grants, are encoded and transmitted from the eNB tothe RN. While the ideas presented herein are primarily described usingrelay type I terminology, they are applicable to other types of relaysas well, notably non-transparent or non-self-backhauling type of relaysamongst others.

A method is described for control channel mapping with multiplexing andinterleaving of R-PDCCHs from multiple relays. If interleaving isapplied, it may be performed on an OFDM symbol basis. R-PCFICH may notbe used.

Methods are described of mapping of the R-PDCCH in the time-frequencygrid, where the R-PDCCH is first mapped along the frequency domainacross the OFDM symbols of the control channel (which also may bereferred to as OFDM control symbols) followed by the time domain. Oneadvantage of the frequency first mapping is to eliminate the use ofR-PCFICH or similar channels.

A tree based assignment of RBs may be used to minimize the resourceallocation overhead. A method is described to configuring the relayspecific configuration parameters. Dedicated R-PDCCH (and downlinkcontrol information (DCI) format) in support of ACK/NACK are described,whereby R-PHICH/PHICH channel performance requirements are typicallymore stringent than a typical R-PDCCH/PDCCH. Signaling of ACK/NACK overR-PDCCH may be employed when R-PHICH is not used.

FIG. 3 shows an example of backhaul control channel mapping. Assignmentsin the frequency domain may be in units of RBs or resource block groups(RBGs) or any other unit thereof. Herein the units may be considered tobe RBs with the understanding that the design scales according to theunits.

In order to maximize the frequency diversity, the relay control channelsmay be mapped uniformly across the entire spectrum. RBs for backhaulcontrol channel may be selected according to the following equation:R _(l)(i)=└i·N _(l,RB) ^(DL) /N _(l,MAX) _(_) _(REL) _(_) _(RB)┘+k,  Equation (1)

where, R_(l)(i)=RB index for lth OFDM Control symbol;

i=0, 1, 2 . . . N_(l,MAX) _(_) _(REL) _(_) _(RB)−1;

N_(l,MAX) _(_) _(REL) _(_) _(RB)=the number of RB's reserved forbackhaul control channel of the lth OFDM control symbol;

N_(l,RB) ^(DL)=Maximum number of RB's in the lth OFDM control symbol;and

k=an integer derived from donor eNb cell ID in a manner similar torelease 8.

The additions are modulo N_(l,RB) ^(DL).

As an example, if N_(l,RB) ^(DL)=20 and N_(l,MAX) _(_) _(REL) _(_)_(RB)=5, thenR _(l)(i)([0 4 8 12 16]+k)mod 20R _(l)(i)=([0,4,8,12,16]+k)mod 20.If k mod 20=0, 1, 2, 3, then R_(l)(i) is in the range of 0 to 19 for alli=0 . . . N_(l,MAX) _(_) _(REL) _(_) _(RB)−1 and no wrap around occursfor OFDM symbol “l”. If k mod 20≥4, then wrap-around occurs. Forexample, if k mod 20=15, thenR _(l)(i)=([0 4 8 12 16]+15)mod 20=[15 19 3 7 11]R _(l)(i)=([0,4,8,12,16]+15)mod 20=[15,19,3,7,11].The RBs with indices 15 and 19 correspond to OFDM symbol “l”, while theRB with indices 3, 7 and 11 (which are the RB where the wrap-aroundoccurs), may be mapped according to this invention to either OFDM symbol“l” or OFDM symbol “l+1”.

One of the following methods may be used to accommodate the modulooperation: 1) use the next OFDM symbol allocated for the backhaulcontrol and continue the mapping; 2) wrap around in the same OFDM symboland populate all available RBs. Once all RBs are utilized, continuemapping over the next OFDM symbol from either a) the next RB locationgiven by Equation (1) above, or b) a RB location given by setting i=0 inEquation (1). N_(l,MAX) _(_) _(REL) _(_) _(RB) may be standardized foreach bandwidth option, or derived from the bandwidth as a fraction ofthe total number of RBs, (e.g., N_(l,MAX) _(_) _(REL) _(_)_(RB)=α·N_(l,RB) ^(DL), where α is a fraction that can take values likeα={1, 1/2, 1/3, 1/4 . . . }). Alternatively, spacing between theadjacent RBs dedicated to backhaul control channels can be specified,andN _(l,MAX) _(_) _(REL) _(_) _(RB) =N _(l,RB) ^(DL)/δ_(RB),  Equation (2)where δ_(RB) is the spacing in units of RB and δ_(RB) can be from apredefined set of integers specified in the standards or a function ofsystem bandwidth.

To provide flexibility and optimize resource allocations, the donor eNBmight not utilize N_(l,MAX) _(_) _(REL) _(_) _(RB) RBs. It is notnecessary to signal the actual number of RBs used. The relay node mayperform blind decoding over a varying number of RBs until it finds therequired number of grants or reaches N_(l,MAX) _(_) _(REL) _(_) _(RB).To reduce the blind decoding complexity, the donor eNB may be restrictedto use only a pre-determined number of RBs, (e.g., from the set {1, 2,4, 8, N_(l,MAX) _(_) _(REL) _(_) _(RB)}).

To permit maximum flexibility in scheduling R8 WTRUs, backhaul controlchannel RB allocations may be made conformant to resource allocationtypes 0, 1 or 2. When a type 2 allocation is used with distributedvirtual resource blocks, control channel can be split between the twotime slots in a manner similar to PDSCH.

Resources can be dedicated to relays in various ways as described above.To introduce greater flexibility and scalability, mapping modes can bedefined and signaled via higher layers. Higher layer signaling could beachieved through system information broadcast (with additionalInformation Element such as control channel RB configuration mode or RBallocation bit map in SIB2 for example), RRC (Radio Resource Control)signaling or NAS signaling. As an example, with 3 bits, 8 modes can bedefined as shown in Table 1 below.

TABLE 1 Mode Mapping 000 N_(1,MAX)_REL_RB in center of band 001N_(1,MAX)_REL_RB uniformly distributed across entire bandwidth 010Resource allocation type 0 with pre configured allocation 011 Resourceallocation type 1 with pre configured allocation 100 Resource allocationtype 2 with pre configured allocation 101 Other configurations 110 Otherconfigurations 111 Other configurations

Preconfigured allocation may imply that the parameters that determinethe exact RBs in each allocation type are standardized. For allocation 0and 1, the value of RBG size, P, and the allocation bit map may beknown. For type 2 allocation, the starting resource block, RB_(start)L_(CRBs), and the step size, N_(RB) ^(step) are standard specified.Alternatively all the parameters may be signaled along with theoperational mode.

The RN might be required to support all backhaul control channel mappingoptions or alternatively a subset of the available backhaul controlchannel mapping options. Alternatively, a default backhaul controlchannel mapping option is specified. The network can signal the backhaulcontrol channel mapping options supported by the network in a systeminformation broadcast message (SIB2 for example) or in RRC signaling ora combination of both. For instance, when the RN is not connected to thenetwork, the RN can acquire the backhaul control channel mappinginformation through system information broadcast messages. On the otherhand, when the RN is in connected mode already, update to backhaulcontrol channel mapping method can be acquired via RRC signaling.

In order to provide full flexibility in scheduling release 8 WTRUs, theRPDSCH may be mapped using one of the resource allocation types used forPDSCH. The R-PDCCH, which may be mapped to RBs, contains the resourceallocation for R-PDSCH.

If the RBs assigned to R-PDSCH also carry the backhaul control channel,then the RB may be time multiplexed with backhaul control channels.

If the R-PDCCH spans multiple time slots, (e.g., when resourceallocation type 2 is used for control channel mapping), then R-PDSCH maybe punctured to accommodate R-PDCCH.

To maximize the frequency interleaving, R-PCFICH (when used) and R-PHICHmay be mapped uniformly across all available backhaul control channelRBs. To maximize the spread, R-PCFICH (when used) and R-PHICH may bemapped in only part (e.g., one third) of the RB.

FIG. 4 shows an example of mapping the R-PHICH and R-PDCCH over an OFDMsymbol when R-PCFICH is not used. FIG. 5 shows an example of mapping theR-PHICH and R-PDCCH over an OFDM symbol when R-PCFICH is used.

The R-PCFICH (when used) may be mapped beginning from a RB whose indexis obtained from the donor eNB cell identity (ID). The R-PHICH may bemapped according to an R8 procedure. In an embodiment, if R-PCFICH 525is mapped to apart of an RB, the other part of the RB may be used byR-PHICH 525 and/or R-PDCCH 520. The remaining RBs may be occupied byR-PDCCH.

The encoded PDCCH for R8 WTRUs are divided into control channel elements(CCEs) and interleaved before being mapped to the time-frequency grid.Mapping is in time-first order. Hence, the number of OFDM controlsymbols must be known before the decoding process can begin.

Time first mapping does not provide any significant advantage in a relayenvironment due to limited or no mobility. The R-PDCCH may be mapped infrequency first order, so that decoding can begin as soon as every OFDMsymbol is processed and made available to control channel processingunit. This avoids the need to signal the number of OFDM control symbols.Example methods display below.

In one embodiment, as shown in FIG. 6A, at block 605 the donor eNBmultiplexes the R-PDCCH of all of the relay nodes in a manner similar toR8. At block 610, the donor eNB may map the multiplexed bit streams toCCEs by simple partitioning of the multiplexed R-PDCCH into units ofCCEs or similar. At block 615, the donor eNB may partition the CCE spaceinto n vectors, where n is the number of backhaul OFDM control symbols.At block 620, the donor eNB transmits data. The method in FIG. 6A allowsa CCE to be mapped across two consecutive OFDM symbols. Also, once theR-PDCCHs for multiple RNs are multiplexed together, the order in whichthe CCEs are mapped to (RBs) is the same as the order of R-PDCCHs in themultiplexed vector. FIG. 6B shows an example of the embodiment where themapping is performed over two OFDM symbols and a CCE may be mappedacross two, OFDM symbols. In other words, for example, the first OFDMsymbol may comprise one or more whole control channel elements (e.g.,CCE #1, #2, and #3) and one partial control channel element (e.g., CCE#4 which spans over OFDM symbol #1 and #2).

The size of the i^(th) vector, where i=1 . . . n (and “n” is the numberof backhaul OFDM control symbols). Note “i” hereinafter is notequivalent to “i” given in Equation (1). R8 techniques are reused formodulation, interleaving and pre-coding. The i^(th) vector is mappedover the i^(th) OFDM symbol reserved for the backhaul OFDM controlsymbol along increasing (or decreasing) order of RBs. The CCEs may bemapped to frequency and time domains. Note that the mapping may beperformed in the frequency first order unlike R8, where the mapping isperformed in time first order. FIG. 6C displays what may occur at thereceiver, for each OFDM control symbol. In general a processor mayreceive from an eNodeB, for example, consecutive first and second OFDMsymbols that represent a plurality of relay physical downlink controlchannels (R-PDCCH) that comprises a first R-PDCCH and a second R-PDCCH.Then the processor may decode the first R-PDCCH from the first OFDMsymbol which is received before the second OFDM symbol. In FIG. 6C atblock 682, the RN performs demodulation and at block 684 constructs nvectors of demodulated bits where the length of i^(th) (i=1 . . . n)vector is equal to the number of bits in the ith OFDM control symbol. Atblock 686, the RN demarcates the ith vector at CCE boundaries where bitsbeyond the integer number of CCEs are considered as a part of thefollowing OFDM control symbol. At block 688, the RN may perform blinddecoding over the CCEs on a per OFDM control symbol basis. This ispossible since interleaving may be performed over the span of a singleOFDM symbol.

If no R-PDCCH addressed to the relay node is found (i.e., No at block690), the RN continues to decode following vector of demodulated bits.There is a “CCE wrap around” that the RN has to account for. If thereare more OFDM control symbols (i.e., Yes at block 694) the bits not usedfor blind decoding in the previous OFDM control symbol are appended tothe vector of bits from the current OFDM symbol. The RN may start againat block 686 and process the reconstructed vector of demodulated bits.

If a R-PDCCH addressed to the relay node is found (i.e., Yes at block690), then the RN checks at block 691 if all monitored R-PDCCH (i.e. allmonitored RNTIs) have been detected. The RN may continue decoding untilthe required number of R-PDCCH are found (i.e., Yes at block 691) or themaximum number of OFDM control symbols are reached (i.e., No at block694). The maximum number of OFDM control symbols can be standardized, ortied to other system parameters like bandwidth, or signaled by higherlayers.

In an embodiment, as shown in FIGS. 7A thru 7C, randomization of themapping the R-PDCCH over the CCE space may be allowed.

At block 705, the donor eNB may multiplex the R-PDCCH of all the relaynodes in a manner similar to R8. At block 710, the donor eNB may computethe number of CCEs that can be mapped over each available OFDM symbol,such that every CCE is mapped within a single OFDM symbol (that is, noCCE spans two OFDM symbols). At block 715, the donor eNB may determinewhat OFDM control symbols to place the given R-PDCCH in. At block 720,the donor eNB, for each symbol, may determine the beginning CCE index ofevery candidate R-PDCCH using a hashing function.

The hashing function may be an eNB specific scheduling algorithm thatoptimizes scheduling or any other parameter. For example, if the R-PDCCHcarries a downlink assignment, to reduce the latency in decoding thedata, the hashing function in the donor eNB may map it to a CCEallocated on the first OFDM control symbol. Similarly, if the R-PDCCHcarries an UL grant, the donor eNB may map it to a CCE allocated to thesecond or third OFDM control symbol (this is because the UL transmissionneeds to be performed 4 ms later, so the latency in decoding the controlchannel is not a main concern). The bashing function may be arandomizing function with input parameters selected from the followingset: sub-frame number, aggregation level, time slot index, or a relayspecific identifier like relay radio network temporary identity (RNTI).For example, CCEs with aggregation level 2 may be mapped to the firstOFDM control symbol in even sub-frames, and to the second OFDM controlsymbol in odd sub-frames. The hashing function may also includemultiplexing of candidate R-PDCCHs followed by simple partitioning intounits of CCE or similar. Additionally, a modulo rotational shift may beapplied where the shift is determined based on some or all of theparameters specified herein.

At block 725, the CCEs for i^(th) OFDM control symbol are multiplexedtogether and NULL bits are added such that after modulation andpre-coding, the ith vector fits completely into the i^(th) symbol, wherei=1 . . . n. At block 730, the modulated and pre-coded symbols aremapped, in frequency first order over the RBs allocated for backhaul.FIG. 7B shows an example of the embodiment where the mapping isperformed over two OFDM symbols and the CCEs may not be mapped acrosstwo OFDM symbols. In other words, for example, the first OFDM symbol maycomprise one or more whole control channel elements (e.g., CCE #1 and#2) and padding (e.g., N which may be padding) if the insertion of a CCEwould go beyond the number of bits available in a OFDM symbol.

FIG. 7C displays what may occur at the receiver, for each OFDM controlsymbol. At block 782 the RN performs demodulation and at block 784constructs n vectors of demodulated bits where the length of i^(th) (i=1. . . n) vector is equal to the number of bits in the ith OFDM controlsymbol. At block 786 the RN demarcates the i^(th) vector at CCEboundaries and discards NULL bits beyond the integer number of CCEs. Atblock 788, the RN may perform blind decoding over the CCEs on a per OFDMsymbol basis. This is possible since interleaving and CCE randomizationmay be performed over the span of a single OFDM control symbol. Using ahashing function identical to the eNB, for each aggregation level, therelay may determine the candidate CCEs over which to perform thedecoding. If no R-PDCCH addressed to the relay node is found (i.e., Noat block 790) and there are more OFDM control symbols (i.e., Yes atblock 794), the RN continues to-decode over the following vector ofdemodulated bits. If a R-PDCCH addressed to the relay node is detected(i.e., Yes at block 790), then at block 791 the RN checks if allmonitored R-PDCCH (i.e., all monitored RNTIs) were detected. The RN maycontinue decoding until the required number of R-PDCCH are found (i.e.,Yes at block 791) or the maximum number of OFDM control symbols arereached (i.e., No at block 794). The maximum number of OFDM controlsymbols may be standardized, or tied to other system parameters likebandwidth, or signaled by higher layers.

Dedicated RBs may be distributed amongst the RNs in a semi-staticfunction. If there are K RBs allocated for relays in an area, then withb bits, K/2^(b) RBs may be assigned to 2^(b) relays or K/2^(b-1) RBs to2^(b-1) relays and so on. Both K and b may be known to the relay nodesvia higher layer signaling or relay system information. Depending on b,the DCI format lengths may change, and the relay nodes may perform blinddecoding accordingly as shown in FIG. 8, which shows reduced bit map forresource allocation.

With one bit, 805, resources may be signaled to two relay nodes. Asshown in FIG. 8, RN 1 at 806 may be assigned the first half of total ofK RBs and RN 2 at 807 may be assigned the next half. With two bits, 810,resources may be signaled to 4 relay nodes. For example RN1, 812, may beassigned the first K/4 RBs. Similarly, with three bits, equal resourcesmay be assigned to eight relays. As shown in FIG. 8, RN 1 may beassigned the first K/8 RBs by sending ‘000’ as the resource allocationin its grant. RN 6, 817, may be assigned the sixth set of K/8 RBs bysending ‘101’ as the resource allocation in its grant. Alternately, forthe example of three bits, if DL backhaul data for less than 8 RN istransmitted in a sub-frame, Relay “X” may be assigned the “Y” sub-set bysending the appropriate 3-bit header. More specifically, if only relays3, 4, 5, 6, 7, 8 are assigned DL resources, RN 3 may be assigned sub-set#0 by signaling ‘000’ in the header, RN 4 may be assigned sub-set #1 bysignaling ‘001’ in the header and so on. The remaining sub-sets (#6 and#7) may be reused by the donor eNB to schedule DL data for the macroWTRUs. This method may be applied when the RBs dedicated to the R-PDSCH(DL backhaul data) for the relays may be split equally between all theRN connected to the eNB. Although this method has less schedulinggranularity in the frequency domain, it has the advantage of lowoverhead, since it does not require the transmission of the resourceallocation bitmap that is employed in resource allocation Type 0 orType 1. Alternately, if the start of each sub-set is also signaled, thenthe restriction for equal resource allocation for the RNs may be lifted.

With backhaul a delay may be included between R-PDCCH and R-PDSCH (DLresource) and between R-PDCCH and R-PUSCH (UL grant) where the delay maybe equal to or greater than 0 in a unit of subframes. This may allow forR-PDCCH to provide DL assignment or UL grants in later sub-frames (i.e.,R-PDCCH to R-PDSCH is δ_(D) sub-frames (δ_(D)>1), and R-PDCCH to -PUSCHis δ_(D)>4). If the R-PDCCH grants uplink resources on the backhaul linkin one or more later sub-frames, the RN knows in advance the sub-framesthat will be used for UL data backhaul. If the R-PDCCH assigns downlinkresources on the backhaul link in one or more later sub-frames, the RNknows in advance what subframes will be needed for UL transmission ofthe ACK/NACK feedback on the backhaul. The RN may then schedule theR-WTRUs such that collisions between the UL access link and the ULbackhaul are avoided (or minimized). Note that the R-WTRUs are the UEsin the RN cell that may be served by the RN.

In order to make UL/DL scheduling in either the backhaul link or accesslink more flexible, the eNB may configure the delay (δ_(D) or δ_(U)) foreach RN (or a group of RNs) semi-statically or dynamically. In case ofsemi-static configuration, a value of the delay is signaled to the RN(s)through higher layers. When it is configured dynamically, the value maybe included in R-PDCCH by introducing a new DCI format where the valueof the delay may be represented by a few bits (e.g., 2 or 3 bits).Alternatively, a delay indicator may be introduced/used in the backhaulcontrol region to indicate a value of δ_(D) or δ_(U). For instance, whena binary delay indicator for DL resources (e.g., R-PDSCH) is used, “0”represents zero delay (e.g., meaning R-PDSCH in the same subframe asR-PDCCH), while “1” means the presence of DL resources (e.g., RPDSCH) inone (or more) later subframe(s) associated with the current subframe.

The delay δ_(D) or δ_(U) may be applied, whereby 1) δ_(D) or δ_(U)corresponds to a delay applied immediately after the sub-frame in whichthe grant is received or 2) the delay, to reduce the number of bits andallow more flexibility, can be relative to a known baseline sub-frame inthe future. For example, in respect with baseline sub-frame, in case ofuplink, the delay may be with respect to sub-frame n+4, where n is thesub-frame in which the grant is received. Furthermore, δ_(D) or δ_(U)may also take negative values which would imply an advancement from thebaseline sub-frame.

In the methods described herein, the parameters to configure the relaynode may be signaled semi-statically or may be preconfigured. When therelay starts up, it may behave as a regular UE. Any relay specificconfiguration parameters may be exchanged via radio resource control(RRC) messages. The relay may use this configuration information totransition from its UE identity to the relay identity.

In R8, the A/N for UL transmission is signaled on the DL PHICH channel.For the relay operation, this may not be optimal or even possible. TheA/N for relay UL backhaul can be sent via a R-PDCCH. The DCI formatcarried by the R-PDCCH may be an extension of the relay specific DCIformats to include A/N information. Alternatively, a special DCI formatmay be created that carries the A/Ns for one or several Relay nodes.This DCI format may be transmitted using an R-PDCCH with a special RNTIthat signifies that the DCI format is intended for A/N. Furthermore, inorder to serve the higher quality requirements for A/N specific R-PDCCH,such an R-PDCCH may be encoded with a low coding rate by using a higheraggregation level than the R-PDCCHs used for UL and DL grants.Additionally, in order to reduce the blind decoding complexity, theaggregation level of such a R-PDCCH may be specified in the standards.

Although features and elements are described above in particular,combinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A method implemented in an evolved Node B (eNB) fortransmitting a relay physical downlink control channel (R-PDCCH) to arelay node (RN), the method comprising: coding a plurality of (R-PDCCH)bits associated with an R-PDCCH transmission, wherein the codedplurality of R-PDCCH bits are mapped first along a frequency domain ofan orthogonal frequency division multiplexing (OFDM) symbol and secondalong a time domain across multiple OFDM symbols; and transmitting theR-PDCCH transmission to the RN, wherein the R-PDCCH transmission ismapped to a set of resource blocks (RBs) and spans the multiple OFDMsymbols, wherein the R-PDCCH transmission is transmitted in a subframethat is a multimedia broadcast multicast services (MBMS) singlefrequency network (MBSFN) subframe.
 2. The method of claim 1, whereinthe set of RBs is predetermined, wherein the predetermined set of RBs isindicated in a radio resource control (RRC) message.
 3. The method ofclaim 1, wherein the R-PDCCH transmission indicates a downlink resourceassignment is included in the subframe containing the R-PDCCHtransmission.
 4. The method of claim 1, wherein the R-PDCCH transmissionbegins at a starting OFDM symbol and is transmitted on a subset of theOFDM symbols included in the subframe containing the R-PDCCHtransmission.
 5. The method of claim 4, wherein the starting OFDM symbolis not the first OFDM symbol of the subframe including the R-PDCCHtransmission.
 6. The method of claim 1, wherein the R-PDCCH bitsassociated with the R-PDCCH transmission are coded on a per OFDM symbolbasis.
 7. The method of claim 1, wherein resource block (RB) allocationsassociated with the R-PDCCH transmission are at least one of a resourceallocation type 0, a resource allocation type 1, or a resourceallocation type
 2. 8. The method of claim 1, wherein the R-PDCCHtransmission occupies resource elements (REs) that otherwise would beused for a physical downlink shared channel (PDSCH).
 9. The method ofclaim 1, wherein the R-PDCCH starts in an OFDM symbol enabling the RN todecode downlink assignments immediately after receiving and processing afirst symbol.
 10. The method of claim 1, wherein the R-PDCCH carries anuplink (UL) grant.
 11. An evolved Node B (eNB) comprising: a processorconfigured to at least: code a plurality of relay physical downlinkcontrol channel (R-PDCCH) bits associated with an R-PDCCH transmission,wherein the coded plurality of R-PDCCH bits are mapped first along afrequency domain of an orthogonal frequency division multiplexing (OFDM)symbol and second in a time domain across multiple OFDM symbols; andtransmit the R-PDCCH transmission to a relay node (RN), wherein theR-PDCCH transmission is mapped to a set of resource blocks (RBs) andspans the multiple OFDM symbols, wherein the R-PDCCH transmission istransmitted in a subframe that is a multimedia broadcast multicastservices (MBMS) single frequency network (MBSFN) subframe.
 12. The eNBof claim 11, wherein the set of RBs are predetermined, wherein thepredetermined set of RBs is indicated in a radio resource control (RRC)message.
 13. The eNB of claim 11, wherein the R-PDCCH bits associatedwith the R-PDCCH transmission are to be coded on a per OFDM symbolbasis.
 14. The eNB of claim 11, wherein resource block (RB) allocationsof associated with the R-PDCCH transmission are at least one of aresource allocation type 0, a resource allocation type 1, or a resourceallocation type
 2. 15. The eNB of claim 11, wherein the R-PDCCHtransmission indicates a downlink resource assignment is included in thesubframe containing the R-PDCCH transmission.
 16. The eNB of claim 11,wherein the R-PDCCH transmission begins at a starting OFDM symbol and istransmitted on a subset of the OFDM symbols included in the subframecontaining the R-PDCCH transmission.
 17. The eNB of claim 16, whereinthe starting OFDM symbol is not the first OFDM symbol of the subframeincluding the R-PDCCH transmission.
 18. The eNB of claim 11, wherein theR-PDCCH transmission is sent to the RN for it to decode downlinkassignments immediately after receiving and processing a first symbol.19. The eNB of claim 11, wherein the R-PDCCH transmission occupiesresource elements (REs) that otherwise would be used for a physicaldownlink shared channel (PDSCH).